(1) personal exemptions and the standard deduction as used on the federal individual income tax return shall be prorated between the two returns, under rules prescribed by the commission in accordance with Title 63G, Chapter 3, Utah Administrative Rulemaking Act, to reflect the proportions of the taxable year during which the individual was a resident and a nonresident; and

(2) the total amount of the taxes due on the two returns may not be less than the total amount of the taxes that would be due if the total of the taxable incomes reported on the two returns had been included in one return.